The ER (endoplasmic reticulum) often shows ribosomes attached to their outer surface. The endoplasmic reticulum bearing ribosomes on their surface is called rough endoplasmic reticulum (RER).

Chloroplast contains small ribosomes. The ribosomes of the chloroplasts are smaller (70S) than the cytoplasmic ribosomes (80S).

The golgi apparatus remains in close association with the endoplasmic reticulum. A number of proteins synthesised by ribosomes on the endoplasmic reticulum are modified in the cisternae of the golgi apparatus before they are released from its trans face. Ribosomes are not present in golgi apparatus.

The inner compartment of mitochondria is called the matrix. The matrix contains ribosomes (70S) and the components required for the synthesis of proteins.